I have 2 dogs, mother (3) and son (1) and for the last couple of months when I walk them, they have started barking at other dogs when on the lead.  When off the lead in the park, althought they see other dogs, they don't bother with then and if they come into contact with one, they like to play with them, so I'm not sure if they feel restricted on the lead.  When walking them individually they are fine, so it seems to only happen when they have each other to back them up.  However I don't want to have to walk them individually. 

Has anyone experienced this problem before and have any suggestions as to how I can walk them together without this problem.

I think what's happened is that as the younger dog has matured they now consider themselves to be a pack.  Would it be possible to walk them seperatly for a few weeks, and work on building YOUR relationship with them, instead of letting them depend on each other.....

Yes I'll have to give that a try.  It seems a shame though as they love having a good run about the park together, but it will hopefully only be for a short time.